1. Field of Invention
The invention relates to a power supply device for driving.
2. Description of Related Art
Conventionally, an electric vehicle, for example, an electric automobile, is equipped with a drive device. In the drive device, revolutions that are generated by the driving of a drive motor are transferred to a drive wheel, causing the electric automobile to run. Furthermore, for example, in the drive device of a hybrid-type vehicle, an engine and a generator are provided as well as the drive motor. Power is generated by the generator through the driving of the engine, and the power that is generated thereby can be stored in a battery.
For example, the drive motor has a rotor, which is provided so as to be rotatable and includes a pair of magnetic poles, and a stator, which is provided outwardly in a radial direction from the rotor and includes a U-phase coil, a V-phase coil and a W-phase coil. In addition, the drive motor is driven by the supply of U-phase current, V-phase current and W-phase current to each coil, enabling the generation of torque from the drive motor, in other words, drive motor torque.
For this purpose, the battery and an inverter are connected, and direct current is supplied from the battery to the inverter. The inverter is structured with a plurality of transistors as power elements, which are switched in a predetermined pattern based on a pulse width modulation signal generated by a drive motor control device, causing current of each of the phases to be generated. In addition, a power supply device for driving is provided in order to generate a required voltage for switching each of the transistors. A power supply circuit portion is connected to the inverter in the power supply device for driving, and U-phase, V-phase and W-phase voltage that is generated in the power supply circuit portion is supplied to the inverter.
Note that FETs may be used for the transistors in the inverter, and three IGBTs that constitute transistor modules may also be used. Furthermore, an IPM (intelligent power module), where the inverter and a drive circuit are integrally formed, may be used. When FETs or IGBTs are used, each FET or each IGBT constitutes a power element.
FIG. 2 is a diagram of a power supply device for driving. In the diagram, reference numeral 21 denotes a power supply circuit portion. Reference numeral 22 denotes an IPM that includes an inverter (not shown in the diagram) for driving a drive motor (not shown in the diagram), and a drive circuit (not shown in the diagram). Reference numeral 23 denotes a drive motor control device that controls the drive motor. Connectors Cn1 and Cn2 are provided in the power supply circuit portion 21, connectors Cn3 and Cn4 are provided in the IPM 22, and connectors Cn5 and Cn6 are provided in the drive motor control device 23.
Note that, in accordance with an ignition (IG) switch (not shown in the diagram) being switched ON, a voltage from a battery (not shown in the diagram), which is a power supply voltage for auxiliary equipment, is supplied as an ignition voltage to the power supply circuit portion 21 through the drive motor control device 23. In addition, the power supply circuit portion 21 is provided with items, such as a transformer (not shown in the diagram) for generating a +15 (V) base voltage based on the ignition voltage, and, on the primary side of the transformer, a FET that interrupts a current and generates a predetermined primary current as a switching element for a power supply, and a switching control circuit (not shown in the diagram) that generates a duty signal, sends the duty signal to the FET, causing the FET to be switched, and, on the secondary side of the transformer, phase power supply circuits for each phase, namely a U-phase power supply circuit, a V-phase power supply circuit, a W-phase power supply circuit, an X-phase power supply circuit, a Y-phase power supply circuit, and a Z-phase power supply circuit, that generate a +15 (V) voltage of each phase in accordance with the switching of the FET, and a feedback circuit that is provided on the primary side in order to, in accordance with the +15 (V) voltages of each phase that are generated on the secondary side, feedback those voltages.
If, for example an abnormality is generated in the switching control circuit, the feedback circuit or the like in the power supply circuit portion 21, causing the generation of a surplus voltage, in other words, an overvoltage, then an overvoltage detection circuit that is provided in each phase power supply circuit detects the overvoltage, generates a detection signal and sends it to a fail detection circuit. If the detection signal is sent to the fail detection circuit, an interface circuit makes a READY signal low level and sends it to the drive motor control device 23. In addition, if the drive motor control device 23 judges that the READY signal is low level, a circuit that supplies the ignition voltage to the power supply circuit portion 21 is cut off, causing operation of the power supply circuit portion 21 to stop.
In this conventional power supply device for driving, however, in the period of time between the overvoltage detection circuit detecting the overvoltage, and the operation of the power supply circuit 21 being caused to stop, it is possible that the IPM 22, more specifically items such as a transistor, a drive circuit or the like (not shown in the diagram) of the IPM 22, may fracture.